This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to determine how a new intranasal (applied inside the nose) gel formulation of male hormone Testosterone called Nasobol[unreadable] is metabolized by human body. This will be done by giving different doses of Nasobol[unreadable] to hypogonadal men (men deficient in male hormone) and measuring how much of these medications remains in blood at set time points. This study will have two groups: hypogonadal men receiving study medication and healthy men not receiving study medication. Blood levels of testosterone in the hypogonadal men will be compared to those in the healthy men. Testosterone levels in healthy men follow a diurnal pattern in which testosterone is high in the morning and gradually declines reaching lowest levels in the early evening. Current marketed formulations of testosterone provide constant serum levels that do not mimic this variation. Nasobol[unreadable] is an innovative pharmaceutical formulation of testosterone for nasal administration that has the potential advantages of ease of use, the possibility to mimic diurnal variation of serum testosterone levels, no risk of transfer to other people like in the testosterone applied on the skin. Currently, there is no available intranasal testosterone gel available for hypogonadal men in the United States.